The influence of temperature on the creep of tin-37 lead solders

Plumbridge, W. J. and Gagg, C. R. (2002). The influence of temperature on the creep of tin-37 lead solders. In: TMS Fall Meeting, 6-10 Oct 2002, Columbus Ohio, USA.



Service conditions experienced by interconnections are becoming increasingly arduous. Temperature ranges are expanding, and upper limits are expected to exceed 0.9 of the melting temperature in K. To provide information for design and life prediction, the creep behaviour of a Sn- 37Pb alloy between 160 and -50°C has been investigated. Significant creep occurs at temperatures as low as -50°C, and the effect of temperature on creep life is profound. For example, at an applied stress of 15MPa, the ratio of rupture times at -50 and 75°C is 2x104. Differences in minimum strain rate are even greater, with a variation of 106 between these temperatures. Creep strengths at 1000h are 33 and 1.5 MPa respectively. The stress sensitivities of rupture time and minimum strain rate diminish slightly with falling temperature. The relationship between applied stress and minimum creep rate behaviour is best described by a power law equation although the steady state domain generally occupies less than 30% of life. Bi-linearity exists in the Monkman-Grant expression, with a transition strain rate at 10-4h-1.

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